AT&T Labs cookin

On the walls of AT&T Labs’s hallways are old photographs of the first transatlantic phone call, five generations of Alexander Graham Bell’s family and other reminders of AT&T’s illustrious history.

But behind every door is a researcher racing to figure out how to move the telephone giant from the circuit-switched world into a packet-switched one.

For all their efforts, though, even Larry Rabiner, AT&T Labs vice-president of research, says the migration from circuit-switched to packet-switched nets is years away.

“We can’t just abandon the plain old telephone system for IP,” Rabiner said. “There first has to be a merging of the two networks.”

Rabiner has charged his staff of more than 2,000 researchers with figuring out a way to protect the company’s century-long investment in the traditional phone network while at the same time taking advantage of the benefits of packet-switched networks, such as lower equipment costs and no regulatory fees.

One of the hottest research projects underway at AT&T Labs — Wireless Integrated Services Protocol (WISP) — is designed to exploit packet-switching benefits. WISP, which was developed by AT&T Labs researchers Cormac Sreenan and Partho Mishra, combines voice and data across wireless LANs.

Bluetooth, a similar project supported by Ericsson, IBM, Intel, Nokia and Toshiba, lets users connect devices, such as laptop computers, mobile phones and printers, without the use of cables. WISP takes this a step further by adding voice calls to the mix.

With WISP, users would be able to relocate their phones and PCs anytime without having to fuss with rewiring and reconfigurations.

The WISP network prototype features a modified handheld device, which is outfitted with a telephone receiver, a wireless LAN interface card and a 48MB Linux-based flashcard, hooked via radio waves to an Ethernet base station located nearby.

The base station, or hub, is connected to the LAN over an ATM backbone. A building could have base stations peppered around its floors. If a user moves out of one base station’s geographic range, another base will pick up the handheld’s signal and become the user’s master base station.

Developing the technology was tricky, Mishra said, because voice has a higher quality-of-service (QoS) requirement than data and, therefore, its packet delivery needs to be scheduled. With WISP, voice calls reserve the bandwidth they need when the call is established. The base station acts as the arbiter of traffic, deciding which packets get priority.

Mishra said the project works well in-house, but moving it outdoors could be challenging. “There isn’t as much bandwidth available as the technology needs,” he said. WISP is about five years from being fully implemented, Mishra said.

Although WISP still has a way to go, Rabiner said the migration to combined voice and data networks will happen sooner.

“We need to create intelligent services based on telephony,” he said. “But the services available today are a world apart from each other. We need universal broadband access from any device. Remember, there are 290 million phones in use today and they aren’t going anywhere.”

— IDG News Service